FIG. 1 shows a table describing a number of wireless communications operating bands in the wireless spectrum. One or more of the operating bands may be used, for example, in a Code Division Multiple Access (CDMA), Global System for Mobile Communications (GSM), Long Term Evolution (LTE), or LTE-advanced equipped wireless communications device. The first column indicates the operating band number for each one of the operating bands. The second and third columns indicate the uplink and downlink frequency bands for each one of the operating bands, respectively. Finally, the fourth column indicates the duplex mode of each one of the operating bands. In non-carrier aggregation configurations, a wireless communications device will generally communicate using a single portion of the uplink or downlink frequency bands within a single operating band. In carrier aggregation applications, however, a wireless communications device may aggregate bandwidth across a single operating band or multiple operating bands in order to increase the data rate of the device.
FIG. 2A shows a diagram representing a conventional, non-carrier aggregation configuration for a wireless communications device. In this conventional configuration, a wireless communications device communicates using a single portion of the wireless spectrum 10 within a single operating band 12. Under the conventional approach, the data rate of the wireless communications device is constrained by the limited available bandwidth.
FIGS. 2B-2D show diagrams representing a variety of carrier aggregation configurations for a wireless communications device. FIG. 2B shows an example of contiguous intra-band carrier aggregation, in which the aggregated portions of the wireless spectrum 14A and 14B are located directly adjacent to one another and are in the same operating band 16. FIG. 2C shows an example of non-contiguous intra-band carrier aggregation, in which the aggregated portions of the wireless spectrum 18A and 18B are located within the same operating band 20, but are not directly adjacent to one another. Finally, FIG. 2D shows an example of inter-band carrier aggregation, in which the aggregated portions of the wireless spectrum 22A and 22B are located in different operating bands 24 and 26. A modern wireless communications device should be capable of supporting each one of the previously described carrier aggregation configurations.
The various carrier aggregation configurations discussed above can be performed between two or more frequency division duplexing (FDD) bands, two or more time division duplexing (TDD) bands, or a combination thereof. Generally, a wireless communications device will aggregate bandwidth when receiving data (i.e., during downlink), but will use a single operating band when transmitting data (i.e., during uplink). However, carrier aggregation may also be used during data transfer to increase uplink throughput.
FIG. 3 shows a schematic representation of conventional radio frequency (RF) front end circuitry 28 configured to support at least one carrier aggregation configuration. The conventional RF front end circuitry 28 includes a first antenna 30A, a second antenna 30B, antenna switching circuitry 32 coupled to the first antenna 30A and the second antenna 30B, RF filtering circuitry 34 coupled between the antenna switching circuitry 32 and a number of input/output nodes 36 (shown individually as 36A through 36H), and transceiver circuitry 38 coupled to the input/output nodes 36. The RF filtering circuitry 34 includes first RF multiplexer circuitry 40A, second RF multiplexer circuitry 40B, and third RF multiplexer circuitry 40C. The first RF multiplexer circuitry 40A is a quadplexer, while the second RF multiplexer circuitry 40B and the third RF multiplexer circuitry 40C are duplexers. Details of the first RF multiplexer circuitry 40A, the second RF multiplexer circuitry 40B, and the third RF multiplexer circuitry 40C are shown in FIGS. 4A through 4C.
FIG. 4A shows a block diagram of the first RF multiplexer circuitry 40A. The first RF multiplexer circuitry 40A includes a first filter 42A coupled between a first common node 44 and a first one of the input/output nodes 36A, a second filter 42B coupled between the first common node 44 and a second one of the input/output nodes 36B, a third filter 42C coupled between the first common node 44 and a third one of the input/output nodes 36C, and a fourth filter 42D coupled between the first common node 44 and a fourth one of the input/output nodes 36D.
FIG. 4B shows a block diagram of the second RF multiplexer circuitry 40B. The second RF multiplexer circuitry 40B includes a fifth filter 42E coupled between a second common node 46 and a fifth one of the input/output nodes 36E and a sixth filter 42F coupled between the second common node 46 and a sixth one of the input/output nodes 36F.
FIG. 4C shows a block diagram of the third RF multiplexer circuitry 40C. The third RF multiplexer circuitry 40C includes a seventh filter 42G coupled between a third common node 48 and a seventh one of the input/output nodes 36G and an eighth filter 42H coupled between the third common node 48 and an eighth one of the input/output nodes 36H.
The RF filtering circuitry 34 is configured to selectively pass RF transmit signals and RF receive signals within a first operating band (band A), a second operating band (band B), and a third operating band (band C) between the antenna switching circuitry 32 and the transceiver circuitry 38. As discussed below, the RF filtering circuitry 34 facilitates at least one carrier aggregation configuration in the conventional RF front end circuitry 28.
A filter response of the first filter 42A includes a pass band configured to pass RF transmit signals within the first operating band (band A) provided at the first one of the input/output nodes 36A to the first common node 44 while attenuating other signals. A filter response of the second filter 42B includes a pass band configured to pass RF receive signals within the first operating band (band A) received at the first common node 44 to the second one of the input/output nodes 36B while attenuating other signals. A filter response of the third filter 42C includes a pass band configured to pass RF transmit signals within the third operating band (band C) between the third one of the input/output nodes 36C and the first common node 44, while attenuating other signals. A filter response of the fourth filter 42D includes a pass band configured to pass RF receive signals within the third operating band (band C) between the first common node 44 and the fourth one of the input/output nodes 36D, while attenuating other signals. A filter response of the fifth filter 42E includes a pass band configured to pass RF transmit signals within the second operating band (band B) between the fifth one of the input/output nodes 36E and the second common node 46, while attenuating other signals. A filter response of the sixth filter 42F includes a pass band configured to pass RF receive signals within the second operating band (band B) between the second common node 46 and the sixth one of the input/output nodes 36F, while attenuating other signals. A filter response of the seventh filter 42G includes a pass band configured to pass RF receive signals within the first operating band (band A) and RF receive signals within the second operating band (band B) between the third common node 48 and the seventh one of the input/output nodes 36F, while attenuating other signals. A filter response of the eighth filter 42H includes a pass band configured to pass RF receive signals within the third operating band (band C) between the third common node 48 and the eighth one of the input/output nodes 36G, while attenuating other signals.
The conventional RF front end circuitry 28 is capable of operating in a standard (i.e., non-carrier aggregation) mode in any one of the first operating band (band A), the second operating band (band B), and the third operating band (band C). To operate in a standard mode in the first operating band (band A), the antenna switching circuitry 32 couples the first RF multiplexer circuitry 40A to the first antenna 30A and the third RF multiplexer circuitry 40C to the second antenna 30B. The transceiver circuitry 38 provides an RF transmit signal within the first operating band (band A) to the first one of the input/output nodes 36A, where it is passed by the first filter 42A to the first common node 44, and, subsequently, to the first antenna 30A via the antenna switching circuitry 32. RF receive signals within the first operating band (band A) received at the first antenna 30A are passed to the first common node 44 via the antenna switching circuitry 32, where they are then passed by the second filter 42B to the second one of the input/output nodes 36B and processed by the transceiver circuitry 38. RF receive signals within the first operating band (band A) received at the second antenna 30B are passed to the third common node 48 via the antenna switching circuitry 32, where they are then passed by the seventh filter 42G to the seventh one of the input/output nodes 36F and processed by the transceiver circuitry 38. The RF receive signals provided to the third RF multiplexer circuitry 40C are generally used as multiple-input-multiple-output (MIMO) diversity receive signals to improve the quality of reception of the conventional RF front end circuitry 28. The antenna switching circuitry 32 may switch the first antenna 30A and the second antenna 30B as desired to improve transmit and/or receive reception from the conventional RF front end circuitry 28.
Without changing the connections made by the antenna switching circuitry 32, the conventional RF front end circuitry 28 may also operate in a standard mode in the third operating band (band C). In such an operating mode, the transceiver circuitry 38 provides an RF transmit signal within the third operating band (band C) to the third one of the input/output nodes 36C, where it is passed by the third filter 42C to the first common node 44, and, subsequently, to the first antenna 30A via the antenna switching circuitry 32. RF receive signals within the third operating band (band C) received at the first antenna 30A are passed to the first common node 44 via the antenna switching circuitry 32, where they are then passed by the fourth filter 42D to the fourth one of the input/output nodes 36D and processed by the transceiver circuitry 38. RF receive signals within the third operating band (band C) received at the second antenna 30B are passed to the third common node 48 via the antenna switching circuitry 32, where they are then passed by the eighth filter 42H to the eighth one of the input/output nodes 36H and processed by the transceiver circuitry 38. The RF receive signals provided to the third RF multiplexer circuitry 40C are generally used as MIMO diversity receive signals to improve the quality of reception of the conventional RF front end circuitry 28. The antenna switching circuitry 32 may switch the first antenna 30A and the second antenna 30B as desired to improve transmit and/or receive reception from the conventional RF front end circuitry 28.
To operate in a standard mode in the second operating band (band B), the antenna switching circuitry 32 couples the second RF multiplexer circuitry 40B to the first antenna 30A and the third RF multiplexer circuitry 40C to the second antenna 30B. The transceiver circuitry 38 provides an RF transmit signal within the second operating band (band B) to the fifth one of the input/output nodes 36E, where it is passed by the fifth filter 42E to the second common node 46, and, subsequently, to the first antenna 30A via the antenna switching circuitry 32. RF receive signals within the second operating band (band B) received at the first antenna 30A are passed to the second common node 46 via the antenna switching circuitry 32, where they are then passed by the sixth filter 42F to the sixth one of the input/output nodes 36F and processed by the transceiver circuitry 38. RF receive signals within the second operating band (band B) received at the second antenna 30B are passed to the third common node 48 via the antenna switching circuitry 32, where they are then passed by the seventh filter 42G to the seventh one of the input/output nodes 36G and processed by the transceiver circuitry 38. The RF receive signals provided to the third RF multiplexer circuitry 40C are generally used as MIMO diversity receive signals to improve the quality of reception of the conventional RF front end circuitry 28. The antenna switching circuitry 32 may switch the first antenna 30A and the second antenna 30B as desired to improve transmit and/or receive reception from the conventional RF front end circuitry 28.
To operate in a carrier aggregation mode of operation using the first operating band (band A) and the third operating band (band C), the antenna switching circuitry 32 couples the first RF multiplexer circuitry 40A to the first antenna 30A and the third RF multiplexer circuitry 40C to the second antenna 30B. The transceiver circuitry 38 then provides an RF transmit signal within one of the first operating band (band A) and the third operating band (band C) to either the first one of the input/output nodes 36A or the third one of the input/output nodes 36C, respectively. RF receive signals within the first operating band (band A) and the third operating band (band C) are passed to the first common node 44 via the antenna switching circuitry 32, where they are then respectively passed by the second filter 42B and the fourth filter 42D to the second one of the input/output nodes 36B and the third one of the input/output nodes 36C and processed by the transceiver circuitry 38. RF receive signals within the first operating band (band A) and the third operating band (band C) are passed to the third common node 48 via the antenna switching circuitry 32, where they are then respectively passed by the seventh filter 42G and the eighth filter 42H to the seventh one of the input/output nodes 36G and the eighth one of the input/output nodes 36H. Accordingly, the conventional RF front end circuitry can transmit a signal in the first operating band or the second operating band while simultaneously receiving signals within both operating bands. The RF receive signals provided to the third RF multiplexer circuitry 40C are generally used as MIMO diversity receive signals to improve the quality of reception of the conventional RF front end circuitry 28. The antenna switching circuitry 32 may switch the first antenna 30A and the second antenna 30B as desired to improve transmit and/or receive reception from the conventional RF front end circuitry 28.
While the conventional RF front end circuitry 28 can be used in carrier aggregation configurations between the first operating band (band A) and the third operating band (band C), the structure of the RF filtering circuitry 34 does not allow for the aggregation of bandwidth between the second operating band (band B) and the third operating band (band C). As discussed above, it is desirable for RF front end circuitry to support as many carrier aggregation configurations as possible for maximum flexibility. Further, the conventional RF front end circuitry 28 requires eight filters. In general, it is desirable to minimize the number of filters used to support these carrier aggregation configurations in order to minimize the space consumed by the RF front end circuitry and the complexity thereof.
In light of the above, there is a need for RF front end circuitry with support for additional carrier aggregation configurations and less filters.